This invention relates generally to handler equipment for processing of semiconductor IC packages. More particularly, it relates to a tube guide of a unique construction for use with an input tube unloader assembly of a handler structure for smoothly guiding the movement of stacked tubes so as to eliminate damage to IC packages therein and/or jamming of the tubes.
As is generally known in the semiconductor industry, there has been a trend toward manufacturing of semiconductor IC chips with higher and higher packing densities. As a result, flat pack or dual-in-line package (DIP) structures for housing semiconductor IC chips has been replaced in recent years by extremely small-sized rectangularly-shaped packages of the type referred to as "plastic leaded chip carrier" (PLCC) packages. Typically, these PLCC packages are of a rectangular shape with varying width and length dimensions. This is due to the fact that the package size is dependent upon the number of terminal leads or pins formed on the four sides of the PLCC package. For example, the number of terminal leads on a PLCC package may be 20, 28, 32, 44, 68 or 84. Further, chip carrier tubes are generally used for housing and/or shipping a relatively large number of these PLCC packages from one work station to another work station or from a chip manufacturer's plant to a customer's location.
In view of these developments, there have also been made significant changes in the design and performance of different types of handler equipment for processing automatically of semiconductor IC packages. Such handler equipment or structures may be used to perform various manufacturing processes, like lead-straightening, lead inspection, marking or mark-inspection for the PLCC packages. One conventional type of handler structure used for a lead-inspection procedure is illustrated in FIG. 1 and is labeled "Prior Art." As can be seen, the handler structure 10 is comprised of a tube unloading station 12, a visual inspection station 14, and a tube loading station 16.
As is well-known in the art, the tube unloading station 12 includes an input tube unloader assembly 18 which receives a plurality of stacked tubes 20. Each of the stacked tubes is previously loaded or completely filled with a plurality of PLCC packages or devices 22. The tubes 20 are preferably formed of a unitary construction and are formed of a suitable plastic or metal material. The tubes 20 are then manually loaded or stacked into a vertical position by an operator. The input tube unloader assembly 18 is used to unload or deliver the PLCC packages 22 housed within each of the respective tubes 20 onto a feed-track 24. The unloader assembly 18 releases the PLCC packages 22 in the lowermost tube 20a onto the feed-track 24, which will guide them in the direction of arrow 25 to the next work station or the visual-inspection station 14. After completion of the visual inspection, the PLCC packages 22 are delivered to the output tube loader 16 for subsequent processing operations.
However, the unloader assembly 18 suffers from the disadvantage that it uses a metal (aluminum) tube guide located adjacent to and contactly engaging the opposite ends of the stacked tubes. The metal tube guide serves to facilitate the movement of the stacked tubes 20 in a downward fashion and onto an unloading area. As can best be seen from FIG. 4, the prior art metal tube guide is formed of an elongated narrow post 26. A plurality of mounting holes 28 extend between the opposite ends of the narrow post 26. The mounting holes 28 are used to firmly secure the post 26 to a main side plate 30 (FIG. 1) of the unloader assembly 18.
In use, it was found that as the respective tubes 20 are being slid downwardly in the direction of arrow 32 there is caused a wearing-out of the mounting holes 28 due to the frictional engagement or rubbing of the ends of the tubes against these holes 28. Further, since the stacked tubes 20 on the unloader assembly 18 are being tilted so as to dispense the PLCC packages 22 from the tubes, it was discovered that the endmost one of the PLCC packages 22 in the respective tubes 20 will come into direct physical contact with the mounting holes and will rub against them. As a consequence, as each of the stacked tubes 20 slides downwardly towards the lower end of the tube guide 26 the leads on the endmost ones of the PLCC packages 22 are highly susceptible to possible physical damage or even destruction.
In order to solve these problems, there has been proposed in the prior art of an improved tube guide of FIG. 5, which is formed of an elongated narrow post 34 with a recessed central portion defining a slot 36. A plurality of mounting holes 38 extend between the opposite ends of the narrow post 34. The plurality of mounting holes 38 are also disposed within the slot 36 so as to protect the same against wearing-out by rubbing. Nevertheless, this prior art solution is not without its own problem. Specifically, as the lowermost tube 20a reaches the bottom of the stack adjacent to the lower end of the narrow post 34, there has been encountered a knocking or jamming of the lowermost tube within the slot 36 in the central portion of the narrow post 34 during an indexing operation for delivering or ejecting sideways in direction of arrow 40 the lowermost tube 20a into a container bin after it has been emptied. As a result, there is caused a jamming of the tubes before they are pushed out or ejected sideways into the container bin.
Therefore, there has arisen still a need for an improved tube guide of a novel design for use with an input tube unloader assembly of a handler structure for smoothly guiding the movement of stacked tubes so as to eliminate damage to IC packages therein and/or jamming of the tubes. This is achieved in the present invention by the provision of a unique tube guide portion having a T-shaped configuration. As a result, the overall mechanical process of the unloader assembly has been significantly enhanced. Since the leads of the PLCC packages are being prevented from being damaged by direct contact with the mounting holes of the tube guides, there will be a smaller rejection rate of the PLCC packages due to deformed or bent leads. In addition, the through-put for the handler operation will be substantially increased as jamming of the tubes will have been reduced or eliminated.